/*
 * Copyright 2002-2018 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      https://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.springframework.web.socket.config.annotation;

import java.util.ArrayList;
import java.util.LinkedHashMap;
import java.util.List;
import java.util.Map;

import org.springframework.context.ApplicationContext;
import org.springframework.lang.Nullable;
import org.springframework.scheduling.TaskScheduler;
import org.springframework.util.Assert;
import org.springframework.util.MultiValueMap;
import org.springframework.web.HttpRequestHandler;
import org.springframework.web.servlet.handler.AbstractHandlerMapping;
import org.springframework.web.socket.WebSocketHandler;
import org.springframework.web.socket.handler.WebSocketHandlerDecorator;
import org.springframework.web.socket.messaging.StompSubProtocolErrorHandler;
import org.springframework.web.socket.messaging.StompSubProtocolHandler;
import org.springframework.web.socket.messaging.SubProtocolWebSocketHandler;
import org.springframework.web.socket.server.support.WebSocketHandlerMapping;
import org.springframework.web.util.UrlPathHelper;

/**
 * A registry for STOMP over WebSocket endpoints that maps the endpoints with a
 * {@link org.springframework.web.servlet.HandlerMapping} for use in Spring MVC.
 *
 * @author Rossen Stoyanchev
 * @author Artem Bilan
 * @since 4.0
 */
public class WebMvcStompEndpointRegistry implements StompEndpointRegistry {

    private final WebSocketHandler webSocketHandler;

    private final TaskScheduler sockJsScheduler;
    private final SubProtocolWebSocketHandler subProtocolWebSocketHandler;
    private final StompSubProtocolHandler stompHandler;
    private final List<WebMvcStompWebSocketEndpointRegistration> registrations = new ArrayList<>();
    private int order = 1;
    @Nullable
    private UrlPathHelper urlPathHelper;


    public WebMvcStompEndpointRegistry(WebSocketHandler webSocketHandler,
                                       WebSocketTransportRegistration transportRegistration, TaskScheduler defaultSockJsTaskScheduler) {

        Assert.notNull(webSocketHandler, "WebSocketHandler is required ");
        Assert.notNull(transportRegistration, "WebSocketTransportRegistration is required");

        this.webSocketHandler = webSocketHandler;
        this.subProtocolWebSocketHandler = unwrapSubProtocolWebSocketHandler(webSocketHandler);

        if (transportRegistration.getSendTimeLimit() != null) {
            this.subProtocolWebSocketHandler.setSendTimeLimit(transportRegistration.getSendTimeLimit());
        }
        if (transportRegistration.getSendBufferSizeLimit() != null) {
            this.subProtocolWebSocketHandler.setSendBufferSizeLimit(transportRegistration.getSendBufferSizeLimit());
        }
        if (transportRegistration.getTimeToFirstMessage() != null) {
            this.subProtocolWebSocketHandler.setTimeToFirstMessage(transportRegistration.getTimeToFirstMessage());
        }

        this.stompHandler = new StompSubProtocolHandler();
        if (transportRegistration.getMessageSizeLimit() != null) {
            this.stompHandler.setMessageSizeLimit(transportRegistration.getMessageSizeLimit());
        }

        this.sockJsScheduler = defaultSockJsTaskScheduler;
    }

    private static SubProtocolWebSocketHandler unwrapSubProtocolWebSocketHandler(WebSocketHandler handler) {
        WebSocketHandler actual = WebSocketHandlerDecorator.unwrap(handler);
        if (!(actual instanceof SubProtocolWebSocketHandler)) {
            throw new IllegalArgumentException("No SubProtocolWebSocketHandler in " + handler);
        }
        return (SubProtocolWebSocketHandler) actual;
    }


    @Override
    public StompWebSocketEndpointRegistration addEndpoint(String... paths) {
        this.subProtocolWebSocketHandler.addProtocolHandler(this.stompHandler);
        WebMvcStompWebSocketEndpointRegistration registration =
                new WebMvcStompWebSocketEndpointRegistration(paths, this.webSocketHandler, this.sockJsScheduler);
        this.registrations.add(registration);
        return registration;
    }

    protected int getOrder() {
        return this.order;
    }

    /**
     * Set the order for the resulting
     * {@link org.springframework.web.servlet.HandlerMapping}
     * relative to other handler mappings configured in Spring MVC.
     * <p>The default value is 1.
     */
    @Override
    public void setOrder(int order) {
        this.order = order;
    }

    @Nullable
    protected UrlPathHelper getUrlPathHelper() {
        return this.urlPathHelper;
    }

    /**
     * Set the UrlPathHelper to configure on the {@code HandlerMapping}
     * used to map handshake requests.
     */
    @Override
    public void setUrlPathHelper(@Nullable UrlPathHelper urlPathHelper) {
        this.urlPathHelper = urlPathHelper;
    }

    @Override
    public WebMvcStompEndpointRegistry setErrorHandler(StompSubProtocolErrorHandler errorHandler) {
        this.stompHandler.setErrorHandler(errorHandler);
        return this;
    }

    protected void setApplicationContext(ApplicationContext applicationContext) {
        this.stompHandler.setApplicationEventPublisher(applicationContext);
    }

    /**
     * Return a handler mapping with the mapped ViewControllers.
     */
    public AbstractHandlerMapping getHandlerMapping() {
        Map<String, Object> urlMap = new LinkedHashMap<>();
        for (WebMvcStompWebSocketEndpointRegistration registration : this.registrations) {
            MultiValueMap<HttpRequestHandler, String> mappings = registration.getMappings();
            mappings.forEach((httpHandler, patterns) -> {
                for (String pattern : patterns) {
                    urlMap.put(pattern, httpHandler);
                }
            });
        }
        WebSocketHandlerMapping hm = new WebSocketHandlerMapping();
        hm.setUrlMap(urlMap);
        hm.setOrder(this.order);
        if (this.urlPathHelper != null) {
            hm.setUrlPathHelper(this.urlPathHelper);
        }
        return hm;
    }

}
